ANSI/BHMA A156.5 Grade 1: 300 in-lbs (34 N.m) Torsional Load Thresholds
Engineering Overview: Engineering analysis of torsional torque testing under ANSI/BHMA A156.5 Grade 1, verifying plug, cam, and key shear resistance under 34 N.m loads.
Technical & Engineering Specifications
| Material | Heat-Treated Sintered 40Cr Steel Cams |
|---|---|
| Standard Reference | ANSI / BHMA A156.5 Section 8.3 |
| Acceptance Criteria | Zero cam shear; cylinder remains operational post-test |
| Required Torsional Torque | 300 in-lbs (33.9 N.m) Torque Threshold |
High Torsional Load Resistance
In commercial panic hardware and exterior deadbolts, heavy leverage applied to a key can shear weak internal cams. ANSI/BHMA A156.5 Grade 1 mandates 300 in-lbs (34 N·m) torsional resistance.
Laboratory Test Sequence
A calibrated digital torque wrench applies 34 N·m rotational torque directly to the key plug. The internal drive cam and retaining screws must not shear or deform.
Frequently Asked Engineering & Selection Questions
Q1: How much torque must an ANSI Grade 1 lock cylinder withstand?
It must withstand at least 300 in-lbs (34 N.m) of turning torque without shearing the cam or breaking the key.